Major Brake Issue

I have been having a brake problem for a while now and i cant seem to fix it. When i brake from anywhere above 50 mph i get a violent shake which almost feels like the backend wants to start skipping. this all started after i replace my front rotors and pads. so i took it to a shop and they said its definitely the back drums and shoes. They replaced the drums and shoes and cleaned and lubed all parts in the rear as well as checked the front rotors for any warping but said front brakes were in good shape. Well...that did not fix the problem so a month later i took it to the toyota dealership and they said the front rotors were warped bad and needed to be resurfaced and that i needed new lower control arms and bushings (i knew my bushings were going bad) so i replaced all that they said as well as did a whole fuel system fix with new fuel filter, pump ,spark plugs, and wires. After spending $2000 on all that it still did not fix the problem. So i brought it back to toyota and took a tech out for a ride so he could feel the problem and of course he felt it and came back. The main tech said its gotta be my tires because the front had some cupping so when i brake im feeling that. well next day i went out and got new tires. Well...still hasnt fixed the problem. So with almost a new front end and new rear drums and shoes and new tires im completely stumped. Ive spent $3000 trying to fix this problem.
Can anyone help me out or has anyone had this same issue??
Also my truck is a 2001 Double cab tacoma limited 2wd

thanks

 

Trucks are designed to stop with a heavy load (max capacity of vehicle). Perhaps wheel hopping due to light load, along w/pulsating of anti-lock brakes, is more pronounce in your particular vehicle.

 

I just recently moved and had my bed loaded with boxes and a motorcycle, so i had a pretty heavy load and it was the same if not worse. Its a violent shake and definitely not supposed to be there. the truck never did it before this point. Im just lost on what to do next.

 

Out of curiousity, what part of the country do you live, or where has the vehicle spent a majority of it's life? I ask bc I'm curious if the underside is full off corrosion. I've seen brake proportioning valves so corroded that they weren't functioning correctly, which could possibly cause a rear vibration/bounce while braking.

Also, have you checked your rear brake shoes to make sure they are fully/properly adjusted? Brake shoes that aren't fully adjusted (have slack/ need to be adjusted) can cause a rear pulsation/ "hop" feeling while braking. I'd start with adjusting the rear shoes and taking a look at the BPV valve while you're under there...

 

Agree with Da Hawaiian. If all 4 brakes received the same amount of pressure, the rear tires would want to lock up, or hop. The brake proportioning valve reduces pressure sent to the rear brakes to alleviate this. If it's (bpv) not functioning correctly, or wasn't bled correctly, it will cause your condition.

 

i just recently moved to Bend OR but the truck has been in southern Cali for its whole life so corrosion is not very likely unless its from the salty air from living by the beach. Ill check the adjustment on the shoes and the BPV valve. I guess thats all i can do...if that doesnt work im not sure what else.
thanks for the help

 

unbalanced tires can cause brake shaking with minimal cruise speed shaking. When applying the brakes you're basically "grabbing" the wheel and you feel the vibrations more. I barely have a drive line shake just cruising but when I brake its like I just hit a washboard.

 

I'm going with the rear proportioning valve as well causing the jump. If that's not correct, it will/can buck jump every time you use the brakes loaded or not.

Have them or some dedicated shop pressure bleed the whole system,,it might free that valve up. Let them know there is a bleeder on that BP valve as well. Bought a pressure bleeder with all the adapters years ago. It's a wonderful thing. I flush that system every 3 years or so.

A quick free check on valve health would be to disconnect the BPV arm and swing it thru its motions,,look and listen. It should be absolutely silent with maybe a clunk when it bottoms out, or tops.

By the looks of it, I would hazard a guess a air bubble was the problem from the start (after the new front brakes were installed).

 

I had a very similar story with one of my dad's work trucks. I finally figured out that the new (cheap aftermarket) pads and rotors did not have the same friction coefficient as the old stock pads and rotors which caused the rears to lock up. In other words, I put crappy brakes on the front so the rears were doing more of the stopping after the change. I put higher quality pads on the front and it was fixed. Only took me 3 weeks and about 600 bucks in parts that I didn't need to figure it out.

 

Sounds like a pro portioning valve issue